Heat exchanger plate

ABSTRACT

Opposite sides of the heat exchanging plate have protuberances engagable with those of similar adjacent plates in a pack, the plates forming interspaces for throughflow of respective heat exchanging media and where such engagement occurs. On at least one side of each plate there are protuberances which are relatively high and protuberances which are relatively low as measured from a central plane of the plate. With adjacent paired plates in undeformed starting positions, only the high protuberances of one plate contact the protuberances of the other plate; but when the plates are sufficiently deformed by an overpressure acting to push them together, the low protuberances of said one plate also contact the protuberances of the other plate, thereby increasing the number of supporting contacts between the paired plates.

. United States Patent [191 [111 3,807,496 1451 Apr. 30, 1974 Stadmark HEAT EXCHANGER PLATE [75] Inventor: Nils Hagert Gote Stadmark, Lund,

Sweden [73] Assignee: Alia-Laval AB, Tumba, Sweden 22 Filed: Oct. 6, 1972 [21 Appl. No.: 295,429

[30] Foreign Application Priority Data" Oct. 5, 1971 Sweden ..f1242s/71 52 us. Cl. .Q 165/167 [51 Int. Cl F28f 3/08 [58] Field of Search 165/166 MF, 167 MF- [56] References Cited UNITED STATES PATENTS 3,229,763 l/l966 Rosenblad 165/166 3,661,203 5/1972 Mesher 2,229,306 1/1941 Prestage 165/167 Primary Examiner-Charles J. Myhre .[57] e ABSTRACT Opposite sides of the heat exchanging plate have protuberances engagable with those of similar adjacent plates in a pack, the plates forming interspaces for throughflow of respective heat exchanging media and where such engagement occurs. On at least one side of each plate there are protuberances which are relatively high and protuberances which are relatively low as measured from a central plane of the plate. With adjacentv paired plates in undeformed starting positions, 'only the high protuberances of one plate contact the protuberances of the other plate; but when the plates are sufficiently deformed by an over-pressure acting to push them together, the low protuberances of said one plate also contact the protuberances 0f the other plate, thereby increasing the number of supporting contacts between the paired plates.

7 Claims, 4 Drawing Figures PATENTEDAPRIBOIQM SHEET 1 BF 2 Fig. 2

HEAT EXCHANGER PLATE THE DISCLOSURE The present invention relates to plate heat exchangers of the kind having a number of thin plates which are put together in a pack of plates and define, together with interposed edge gaskets, closed plate interspaces with inlets and outlets for two heat exchanging media. More particularly, the invention relates to a new plate for plate heat exchangers of this kind, which on both sides of its heat transferring portion has pressed protuberances intended to contact adjacent plates in a plate heat exchanger for serving as turbulence-effecting and spacing means in the plate interspaces.

Heat exchanging plates of this kind are provided with protuberances in their heat transferring portions for different reasons. Firstly, turbulence of the media flowing between the plates is desired. Secondly, an enlarged effective heat exchanging surface of each plate is desired. Thirdly, many support points are desired over the heat transferring portion of the plate, so that the plate material may be made as thin as possible with respect to the desired strength or. physical properties of the plate. Among other things, the plate must be able to resist a certain pressure difference between the heat exchanging media.

For most applications, a great number of support points between the heat exchanging plates causes no problem. However, within certain parts of the industry I it is desired that the heat exchanging plates support each other on their heat exchanging surfaces in as few points as possible. Withinthe food-stuff industry, for instance, where the requirements of hygiene are very high, it is considered that the support points create areas of the plate which are difficult to clean.

If the number of support points for the heat transferring portion of a plate is reduced, however, ,the plate must be made of thicker material in order not to become less capable of resisting pressure differences between the heat exchanging media. This means that the production costs are increased, among other things because special plates must be made for different needs.

An object of the present invention is to provide a construction for heat exchanging plates of the abovementioned kind, by means of which it is possible to satisfy both the need for a plate able to resist great pres- I sure differences between the heat exchanging media in a plate heat exchanger (i.e., a plate having several support points in the heat exchanging surface) and the need for a plate that can be effectively cleaned while it is assembled in a plate heat exchanger (i.e., a plate having few support points in the heat exchanging surface).

According to the invention, this object is fulfilled by a heat exchanging plate having on at least one of its sides first protuberances distributed over the heat transferring portion and having a certain height above the central plane of the plate, and second protuberances distributed over the same portion among the said first protuberances and having less height above the central plane of the plate. The different protuberances are so located in relation to each other that from a starting position in which the plate so contacts a similar plate that the plates cover each other, and only the highest protuberances of each plate abut the other in the operating interspace existing before the said deformation.

With this construction, the same pressing tool may be used for the production of heat exchanging plates which are usable both in cases where great pressure differences between two heat exchanging media occur and in cases where effective and easy cleaning of the plates is required.

Plates produced according to the invention may be used in different manners. For example, when the plates are to be used with great pressure differences between the heat exchanging media, they are immediately so deformed in connection with their assembly in a heat exchanger that, the high as well as the low protuberances on the heat transferring portions of each plate willabut those of the adjacent plates. If the plates are not to be used later in cases where a smaller number of support points is desired between the plates, this deformation may be allowed to become permanent.

As an alternative, the plates in connection with their assembly may be arranged so that in operating position only the highest protuberances will abut the adjacent plates. Thus, the need for onlya small number of support points on the heat exchanging surface is satisfied. In spite of this, however, the plates in this arrangement also satisfy the requirement of resisting pressure differences between the two heat exchanging media, as the orily thingthat will happen at an increased pressure of one of the media is that in the low pressure interspaces the lower protuberances will also be brought into abutment against the adjacent plates. This will be obtained by deformation of the plate material. The number of support points will then be so large in the low pressure interspaces that the increased pressure difference between the two heat exchanging media can be resisted by the plates without further deformation of the same. In this case, the difference in height between the different kinds of protuberances in the plate should be very small, so that a deformation of the aforesaid kind will not be permanent.

In the two above-described manners of using plates constructed according to the invention, edge gaskets of different thickness may be required. In the case where the plate material is deformed by means of an increased medium pressure, the protuberances close to the edge gaskets should be placed so near each other that the same distance between the central planes of the respective platesis maintained at the edge gaskets in spite of the-increased medium pressure.

According to a preferred embodiment of the new heat exchanging plate, the highest protuberances on one side of the plate are so located in relation to the lower protuberances on the other side of the plate that an increased medium pressure against the said one side of the plate will move the highest protuberances on this side of the plate, by temporary deformation of the plate, in the direction towards the central plane of the plate, while the lower protuberances on the other side of the plate are moved in the direction away from this central plane. In a plate heat exchanger assembled from plates of this kind, it is possible to obtain a very effective cleaning of the plates by introducing in every second plate interspace cleaning liquid under high pressure, so that all of the contact points between the plates are occasionally released in these plate interspaces. If desired, the rest of the plate interspaces may then be cleaned in the same way.

In the following, a preferred embodiment of the invention will be described with reference to the accompanying drawing. In the drawing,

- FIG. 1 is a side elevational view of a plate heat exchanger of the kind involved here;

FIG. 2 is a face view of one of the plates for the exchanger;

FIG. 3 is a cross-sectional view of portions of three clamped together in a conventional manner in the frame. The heat exchanging plates, contacting each other in the heat exchanger, form together with interposed edge gaskets closed plate interspaces with inlets and outlets for two heat exchanging media. In FIG. 2 there is shown a heat exchanging plate 3 with an edge gasket 4. Four holes 5-8 in the heat exchanging plate form the said inlets and outlets for the two heat exchanging media flowing to and from the respective plate interspaces formed in the plate heat exchanger on opposite sides of the illustrated plate 3. In the plate heat exchanger, the holes 5-8 are connected in a conventional manner with inlet and outlet studs 9 and 10 on the frame 1 of the heat exchanger (FIG. 1).

Each plate 3 is divided on each side into three different fields, namely, two so-called distribution surfaces I each other only at this point 17 in the parts of the plates shown in FIG. 4. If the pressure in every second interspace is then increased above a predetermined value (the pressure in the interspace between the plates 3b and 3c is assumed to be kept unchanged), all of the plates are so deformed that the somewhat higher ridges 14a on the low pressure side of each plate (see for instance the ridges 140 on the underneath side of the plate 3b in FIG. 3) are lowered, i.e., are pressed in the direction towards the central plane of the plate by the adjacent plate (for instance the plate in FIG. 3). Thus, the somewhat lower ridges 14b on the same side of the plate-are brought'somewhat closer to the adjacent plate (for instancethe plate 3c in FIG. 3). At the same time, theover-pressure in every second plate interspace also exerts a deforming action directly on the plates defining the over-pressure interspaces. In other words, the over-pressure between, for instance, the plates 3a and 3b causes the somewhat higher ridges 14a in this high pressure interspace to be brought out of contact with each-other,-the somewhat lower ridges 14b on the low pressure side of the plate-3b (the underneath side in FIG. 3) being simultaneously brought closer to the plate 3c.

11 and I2 and the main heat exchanging surface 13.

The distribution surfaces 11 and 12 as well as the heat exchanging surface 13 are provided on both sides of the plate with protuberances in the form of ridges formed in the plate. The ridges on one side of the plate are shown by full lines 14. The ridges on the other side of the plate extend parallel to and between these lines 14.

In the assembled plate heat exchanger according to FIG. 1 the plates are preferably identical, but every second plate 3 is so arranged relative to the other plates that the ridges 14 of adjacent plates 3 cross each other in the interspaces formed by the plates.

In FIG. 3, portions of three plates 30, 3b and 3c are shown. As can be seen, the plate 3b on both sides has ridges of different height as measured from the central plane of the plate, this central plane being shown at 15. The higher ridges 14a abut the adjacent plates 3a and 3c, respectively, while the lower ridges 14b are spaced from these adjacent plates. Also, the plates 3a and 3c have ridges 14a and 14b of different height, as can be seen from FIG. 3.

In FIG. 2 there is shown a square 16, the area of which corresponds to that of the plate portions in FIG.

As can be seen from FIG. 3, one ridge 14a on the underneath side of the plate 3b contacts or abuts a crossing ridge 14a on the plate 3c. The position of this contact point 17 can be seen in FIG. 4. In a starting position, when exactly the same pressure is prevailing in all of the plate interspaces, the plates 3b and3c contact Due to this effect of a certain higher pressure in every second plate interspace than in the others in the plate heat exchanger, it can be achieved that in certain plate interspaces all the support between the plates is eliminated, while in the remaining plate interspaces the number of contact or support points increases substantially. In the embodiment shown in FIGS. 3 and 4, the number of contact points in a low pressure interspace may in this way become nine times greater than in a starting position, when substantially the same pressure is prevailing in all of the plate interspaces. This is illustrated in FIG. 4, where the reference numerals l8 designate eight contact points created between the paired plates 31; and 3c*as the result of an over-pressure in the interspaces above andbelow these paired plates, the contact points 18 being in addition to the initial contact point 17. I

As shown in FIGS 3 and 4, the parallel ridges on the upper side of plate 3b include two low ridges 14b extending between two high ridges 14a, and the groove between these two low ridges 14b forms the back (upper) side of a high ridge 14a on'the other (lower) side of the plate. Also, the slope from the crest of each ridge to the bottom of the valley between adjacent ridges is provided with a shoulder located in the central plane 15.

I claim:

1. A heat exchanging plate adapted for use in a plate heat exchanger of the type having a pack of plates with marginal gaskets interposed between adjacent paired plates to define closed plate interspaces provided with inlets and outlets for flow of two heat exchanging media through respective interspaces, said plate having a central plane and also having a deformable heat transferring portion provided on each side of the plate with pressed protuberances integral with the plate and projecting away from said central plane for contact with an adjacent paired plate, said protuberances on at least one side of the plate including protuberances which are relatively high and protuberances which are relatively low as measured from said central plane, the low protuberances beingdistributed among the high protuberances over said heat transferring portion, the

plate being pairable with a similar plate to form paired plates having starting positions wherein only the high protuberances of one plate contact the protuberances of the other plate, the paired plates being deformable from their starting positions to bring the low protuberances of said one plate into contact with the protuberances of said other plate, whereby the paired plates form an interspace in which the plates contact each other at more points when thus deformed than when in their said starting positions.

2. A plate according to claim 1, in which both sides of the plate have said relatively high and low protuberances, said high protuberances on one side of the plate being so located relative to the low protuberances on the other side of the plate that an increased medium pressure on said one side of the plate temporarily deforms the plate to move the high protuberances on said one side in the direction toward said central plane of the plate, while the low protuberances on said other side are moved in the direction away from said central plane.

-3. A plate according to claim 1, in which said protuberances comprise parallel ridges formed in the plate.

4. A plate according to claim 3, in which said ridges on each side of the plate include two low ridges extending between two high ridges.

5. A plate according to claim 4, in which said two low ridges on one side of the plate form between them a groove constituting the back side of a high ridge on the other side of the plate.

6. A plate according to claim 3, in which on one side of the plate a valley is formed between adjacent ridges, the slope between the crest of each of said adjacent ridges and the bottom of said valley being provided with a shoulder.

7. In a plate heat exchanger of the type having a pack of heat exchanging plates with marginal gaskets interposed between adjacent plates to define closed plate interspaces provided with inlets and outlets for flow of two heat exchanging media through respective interspaces, a pair of said plates each having a central plane and also having a deformable heat transferring portion provided on each side of the plate with pressed protuberances integral with the plate, the protuberances on each said side projecting away from the central plane of the plate and including protuberances which are relatively high and protuberances which are relatively low as measured from said central plane, the low protuberances being distributed among the high protuberances over said heat transferring portion, said paired plates having starting positions wherein only the high protuberances of one plate contact the protuberances of the starting positions. 

1. A heat exchanging plate adapted for use in a plate heat exchanger of the type having a pack of plates with marginal gaskets interposed between adjacent paired plates to define closed plate interspaces provided with inlets and outlets for flow of two heat exchanging media through respective interspaces, said plate having a central plane and also having a deformable heat transferring portion provided on each side of the plate with pressed protuberances integral with the plate and projecting away from said central plane for contact with an adjacent paired plate, said protuberances on at least one side of the plate including protuberances which are relatively high and protuberances which are relatively low as measured from said central plane, the low protuberances being distributed among the high protuberances over said heat transferring portion, the plate being pairable with a similar plate to form paired plates having starting positions wherein only the high protuberances of one plate contact the protuberances of the other plate, the paired plates being deformable from their starting positions to bring the low protuberances of said one plate into contact with the protuberances of said other plate, whereby the paired plates form an interspace in which the plates contact each other at more points when thus deformed than when in their said starting positions.
 2. A plate according to claim 1, in which both sides of the plate have said relatively high and low protuberances, said high protuberances on one side of the plate being so located relative to the low protuberances on the other side of the plate that an increased medium pressure on said one side of the plate Temporarily deforms the plate to move the high protuberances on said one side in the direction toward said central plane of the plate, while the low protuberances on said other side are moved in the direction away from said central plane.
 3. A plate according to claim 1, in which said protuberances comprise parallel ridges formed in the plate.
 4. A plate according to claim 3, in which said ridges on each side of the plate include two low ridges extending between two high ridges.
 5. A plate according to claim 4, in which said two low ridges on one side of the plate form between them a groove constituting the back side of a high ridge on the other side of the plate.
 6. A plate according to claim 3, in which on one side of the plate a valley is formed between adjacent ridges, the slope between the crest of each of said adjacent ridges and the bottom of said valley being provided with a shoulder.
 7. In a plate heat exchanger of the type having a pack of heat exchanging plates with marginal gaskets interposed between adjacent plates to define closed plate interspaces provided with inlets and outlets for flow of two heat exchanging media through respective interspaces, a pair of said plates each having a central plane and also having a deformable heat transferring portion provided on each side of the plate with pressed protuberances integral with the plate, the protuberances on each said side projecting away from the central plane of the plate and including protuberances which are relatively high and protuberances which are relatively low as measured from said central plane, the low protuberances being distributed among the high protuberances over said heat transferring portion, said paired plates having starting positions wherein only the high protuberances of one plate contact the protuberances of the other plate, the paired plates being deformable from their starting positions to bring the low protuberances of said one plate into contact with the protuberances of said other plate, whereby the paired plates form an interspace in which the plates contact each other at more points when thus deformed than when in their said starting positions. 